Neospora caninum seropositivity in cattle breeds in the South Fluminense Paraíba Valley, state of Rio de Janeiro

The infection by Neospora caninum of different cattle breeds in dairy properties in two municipalities of the South Fluminense Paraíba Valley, state of Rio de Janeiro, was evaluated. Considering a sampling universe of 2,491 cows, blood samples were collected from 563 dairy cows in 57 farms, which were randomically selected in proportion to the number of animals, using a random stratified sampling system. For each property the number of selected cows was proportional to the herd size. Abortion or other reproductive disorders were not considered as criteria for selecting the animals, and seropositivity was determined by indirect enzyme-linked immunosorbent assay (ELISA). A high association (p=0.006) between seropositivity and racial patterns was found. The analysis revealed that in comparison of pure black-and-white Holstein cows versus Zebu (p=0.0028), Holstein cows showed 2.65 times greater odds for seropositivity. In the same way, by comparing black-and-white Holstein versus Zebu + crossbreed Zebu/Holstein (p=0.01), it was noted that there is 2.23 times more chance for seropositivity in Holstein cattle. There were no significant differences concerning the comparison of Holstein cattle versus crossbreed Zebu/Holstein (p=0.08) or Zebu versus crossbreed Zebu/Holstein (p=0.11). This study supports the hypothesis that there is a close association between cattle breeds and the frequency of infection by N. caninum.

Leukograms of healthy Holstein calves within the first month of life

To establish reference values and to assess the influence of age on the leukograms of healthy Holstein calves, blood samples were obtained from 300 animals. These samples were distributed equally (n=20) among 15 experimental groups according to age: birth to 8 hours, 9 to 16 hours, 17 to 24 hours, 2 days, 3 days, 4 days, 5 days, 6 to 7 days, 8 to 9 days, 10 to 11 days, 12 to 13 days, 14 to 15 days, 16 to 20 days, 21 to 25 days and 26 to 30 days of age. The maximum numbers of leukocytes (9,305.0/mL), segmented neutrophils (6,551.2/mL) and total neutrophils (6,678.3/mL) were noted within the first 8 hours of life, while band neutrophils peaked in number (133.3/mL) between 9 and 16 hours after birth. Meanwhile, the maximum total lymphocyte (4,992.1/µL) and typical lymphocyte (4,686.1/µL) counts occurred between 21 and 25 days, whereas atypical lymphocytes (388.5/µL) reached their maximum number between 26 and 30 days, demonstrating an inversion of the neutrophil:lymphocyte ratio over time. Thus, the influence of age on the leukocyte count of the evaluated calves was verified. The release of endogenous corticosteroids during labor or at birth may contribute to this variation in leukograms with age.

Effect of pregnancy on the genetic evaluation of dairy cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Persistent efficacy of 3.5% doramectin compared to 3.15% ivermectin against gastrointestinal nematodes in experimentally-infected cattle in Brazil

The present study aimed to evaluate the persistent efficacy of a 3.5% doramectin* (700μg/kg) formulation compared to 3.15% ivermectin** (630μg/kg) treatment, administered subcutaneously at a dose of 1mL/50kg body weight in cattle experimentally infected with gastrointestinal nematodes. Seventy-two male crossbred Holstein cattle that were negative for helminth infection were divided into nine groups. Treatments of 3.5% doramectin (Groups 2, 4, 6 and 8) and 3.15% ivermectin (Groups 3, 5, 7 and 9) were administered on days 49, 42, 35 and 28 prior to challenge with infectious nematode larvae (L3). Animals in the control group (Group 1) received saline solution on day 49 before challenge. Beginning on day zero, each animal received 50mL orally of a mixed culture containing approximately 3,000 third stage larvae (L3) of Haemonchus (60%), Oesophagostomum (20%), Cooperia (15%) and Trichostrongylus (5%) for seven consecutive days, resulting in a total challenge of 21,000 larvae/animal. Due to the large number of cattle, autopsies were performed between days 28 and 35 after the last day of inoculation. The formulation containing doramectin (700 mcg/kg) achieved persistent efficacy against H. placei and C. punctata for 49 and 35days, respectively. The persistent efficacy of ivermectin (630 mcg/kg) against H. placei lasted for 49days, but this treatment was ineffective against C. punctata. Both formulations demonstrated persistent efficacy against T. axei for 49days. The persistent efficacy of doramectin (700 mcg/kg) and ivermectin (630 mcg/kg) lasted for 49 and 42days against O. radiatum, respectively. © 2012 Elsevier Ltd.

Reaction norm model to describe environmental sensitivity across first lactation in dairy cattle under tropical conditions

Reaction norm models have been widely used to study genotype by environment interaction (G × E) in animal breeding. The objective of this study was to describe environmental sensitivity across first lactation in Brazilian Holstein cows using a reaction norm approach. A total of 50,168 individual monthly test day (TD) milk yields (10 test days) from 7476 complete first lactations of Holstein cattle were analyzed. The statistical models for all traits (10 TDs and for 305-day milk yield) included the fixed effects of contemporary group, age of cow (linear and quadratic effects), and days in milk (linear effect), except for 305-day milk yield. A hierarchical reaction norm model (HRNM) based on the unknown covariate was used. The present study showed the presence of G × E in milk yield across first lactation of Holstein cows. The variation in the heritability estimates implies differences in the response to selection depending on the environment where the animals of this population are evaluated. In the average environment, the heritabilities for all traits were rather similar, in range from 0.02 to 0.63. The scaling effect of G × E predominated throughout most of lactation. Particularly during the first 2 months of lactation, G × E caused reranking of breeding values. It is therefore important to include the environmental sensitivity of animals according to the phase of lactation in the genetic evaluations of Holstein cattle in tropical environments.

Leukograms of healthy Holstein calves within the first month of life

To establish reference values and to assess the influence of age on the leukograms of healthy Holstein calves, blood samples were obtained from 300 animals. These samples were distributed equally (n=20) among 15 experimental groups according to age: birth to 8 hours, 9 to 16 hours, 17 to 24 hours, 2 days, 3 days, 4 days, 5 days, 6 to 7 days, 8 to 9 days, 10 to 11 days, 12 to 13 days, 14 to 15 days, 16 to 20 days, 21 to 25 days and 26 to 30 days of age. The maximum numbers of leukocytes (9,305.0/mL), segmented neutrophils (6,551.2/mL) and total neutrophils (6,678.3/mL) were noted within the first 8 hours of life, while band neutrophils peaked in number (133.3/mL) between 9 and 16 hours after birth. Meanwhile, the maximum total lymphocyte (4,992.1/µL) and typical lymphocyte (4,686.1/µL) counts occurred between 21 and 25 days, whereas atypical lymphocytes (388.5/µL) reached their maximum number between 26 and 30 days, demonstrating an inversion of the neutrophil:lymphocyte ratio over time. Thus, the influence of age on the leukocyte count of the evaluated calves was verified. The release of endogenous corticosteroids during labor or at birth may contribute to this variation in leukograms with age.

Erytrogram of healthy female Holstein calves during the first month of life

Benesi F.J., Teixeira C. M. C., Lisboa J.A.N., Leal M. L. R., Birgel Jr E. H., Bohland E. & Mirandola R. M. S. 2012. [Erytrogram of healthy female Holstein calves during the first month of life.] Eritrograma de bezerras sadias, da raca Holandesa, no primeiro mes de vida. Pesquisa Veterinaria Brasileira 32(4): 357-360. Departamento de Cl nica Medica, Faculdade de Medicina Veterinaria e Zootecnia, Universidade de Sao Paulo, Campus Universitario, Av. Prof. Dr. Orlando Marques de Paiva 87, Sao Paulo, SP 05508-000, Brazil. E-mail: febencli@usp.br In order to establish reference values, and to assess the in fluence of the age factor on the erytrogram of healthy Holstein calves, blood samples from 300 animals were used, spread over 15 experimental groups, according to age, in the first month of life. Variations of the average values for the components of erytrogram were as follows: number of red blood cells (x10(6)/mm(3)) = 6.68-7.60, packed cell volume (%) = 29.80-33.35, hemoglobin concentration (g/dl) = 9.00-10.43, mean corpuscular volume (fl) = 38.93-47.68, mean corpuscular hemoglobin (pg) = 11.75-14.69, mean corpuscular hemoglobin concentration (%) = 29.53-31.63% and number of reticulocytes (x10(3)/mm(3)) = 0.00-11.86. The in fluence of the age factor proved to be significant for the mean corpuscular volume, mean corpuscular hemoglobin and the number of reticulocytes.

Independent polled mutations leading to complex gene expression differences in cattle

The molecular regulation of horn growth in ruminants is still poorly understood. To investigate this process, we collected 1019 hornless (polled) animals from different cattle breeds. High-density SNP genotyping confirmed the presence of two different polled associated haplotypes in Simmental and Holstein cattle co-localized on BTA 1. We refined the critical region of the Simmental polled mutation to 212 kb and identified an overlapping region of 932 kb containing the Holstein polled mutation. Subsequently, whole genome sequencing of polled Simmental and Holstein cows was used to determine polled associated genomic variants. By genotyping larger cohorts of animals with known horn status we found a single perfectly associated insertion/deletion variant in Simmental and other beef cattle confirming the recently published possible Celtic polled mutation. We identified a total of 182 sequence variants as candidate mutations for polledness in Holstein cattle, including an 80 kb genomic duplication and three SNPs reported before. For the first time we showed that hornless cattle with scurs are obligate heterozygous for one of the polled mutations. This is in contrast to published complex inheritance models for the bovine scurs phenotype. Studying differential expression of the annotated genes and loci within the mapped region on BTA 1 revealed a locus (LOC100848215), known in cow and buffalo only, which is higher expressed in fetal tissue of wildtype horn buds compared to tissue of polled fetuses. This implicates that the presence of this long noncoding RNA is a prerequisite for horn bud formation. In addition, both transcripts associated with polledness in goat and sheep (FOXL2 and RXFP2), show an overexpression in horn buds confirming their importance during horn development in cattle.

Genome-Wiide estimates of coancestry, in breeding and effective population size in the Spanish Holstein population

Estimates of effective population size in the Holstein cattle breed have usually been low despite the large number of animals that constitute this breed. Effective population size is inversely related to the rates at which coancestry and inbreeding increase and these rates have been high as a consequence of intense and accurate selection. Traditionally, coancestry and inbreeding coefficients have been calculated from pedigree data. However, the development of genome-wide single nucleotide polymorphisms has increased the interest of calculating these coefficients from molecular data in order to improve their accuracy. In this study, genomic estimates of coancestry, inbreeding and effective population size were obtained in the Spanish Holstein population and then compared with pedigree-based estimates. A total of 11,135 animals genotyped with the Illumina BovineSNP50 BeadChip were available for the study. After applying filtering criteria, the final genomic dataset included 36,693 autosomal SNPs and 10,569 animals. Pedigree data from those genotyped animals included 31,203 animals. These individuals represented only the last five generations in order to homogenise the amount of pedigree information across animals. Genomic estimates of coancestry and inbreeding were obtained from identity by descent segments (coancestry) or runs of homozygosity (inbreeding). The results indicate that the percentage of variance of pedigree-based coancestry estimates explained by genomic coancestry estimates was higher than that for inbreeding. Estimates of effective population size obtained from genome-wide and pedigree information were consistent and ranged from about 66 to 79. These low values emphasize the need of controlling the rate of increase of coancestry and inbreeding in Holstein selection programmes.

Digital dermatitis of the accessory digits of dairy cows

This report characterizes the digital dermatitis (DD) lesions in the accessory digits of dairy cows and presents data on the applied therapy. Fifteen Holstein cattle with DD affecting the accessory digits of the hindlimbs from four dairy farms with previous history of DD were evaluated. Lesions were excised, the wounds were sutured, and a topical application of oxytetracycline powder covered by bandaging was associated with a single parenteral administration of long acting oxytetracycline IM (20mg/kg). Tissue samples were obtained for histopathology and transmission electronic microscopy (TEM). Lesions from all the animals were recuperated 15 days after surgical procedure. Overal, most DD lesions were papillomatous epidermal projections or wartlike verrucous lesions. Histopathologically, samples revealed hyperplasia of epidermis with hyperkeratosis, several mitoses in the stratum basale and elongated rete ridges in the superficial and middle dermis. TEM revealed long, thin spirochete-like bacteria. Morphologic features of lesions and its response to therapy were comparable to those described for DD.

Características do pelame de vacas Holandesas em ambiente tropical: um estudo genético e adaptativo

As características do pelame (espessura da capa, comprimento médio dos pêlos, número de pêlos por unidade de área, densidade de massa dos pêlos, ângulo de inclinação dos pêlos com respeito a superfície da epiderme e diâmetro médio do pêlos) foram avaliadas em 973 vacas da raça Holandesa, entre novembro de 2000 e abril de 2001, numa área localizada 20cm abaixo da coluna vertebral, no centro do tronco, tanto nas malhas brancas como nas negras. As amostras de pêlos foram obtidas com um alicate comum adaptado. O método da Máxima Verossimilhança Restrita (REML) foi usado para estimar os componentes de variância e covariância sob modelo animal, sendo empregado o sistema MTDFREML. Os resultados mostraram que as características do pelame preto são diferentes das do branco, quando os animais são criados em ambiente tropical. O pelame preto apresentou-se menos denso, com pêlos mais curtos e grossos devido à maior necessidade de perder calor, enquanto que, o pelame branco é mais denso e com pêlos mais compridos, oferecendo uma melhor proteção contra à radiação solar direta. A seleção de vacas predominantemente negras pode ser uma boa escolha para aumentar a resistência do gado Holandês às condições do ambiente tropical, principalmente à radiação solar, quando esses animais são criados a campo, devido a que a epiderme sob esse tipo de malhas é altamente pigmentada. Tal seleção pode ser facilmente realizada, considerando a alta herdabilidade (h²=0,75) para a proporção de malhas negras. Esta seleção deve ser realizada no sentido de um pelame menos denso, com pêlos curtos e grossos favorecendo as perdas de calor sensível e calor latente.

Digital dermatitis of the accessory digits of dairy cows

Esse estudo caracteriza lesões de dermatite digital (DD) nos dígitos acessórios de vacas leiteiras, além de apresentar a terapia aplicada. Foram utilizados 15 bovinos leiteiros da raça Holandês com DD nos dígitos acessórios dos membros pélvicos. Os animais eram provenientes de quatro fazendas leiteiras com histórico prévio de dermatite digital (DD). Todos os quinze animais foram tratados da mesma forma: após excisão das lesões e sutura das feridas cutâneas, aplicou-se oxitetraciclina pó topicamente sob bandagem e oxitetraciclina (20mg/kg) de longa ação, via intramuscular. Obtiveram-se amostras de tecidos para histopatologia, inclusive por microscopia eletrônica de transmissão (MET). Observou-se cicatrização em todos os animais após 15 dias do procedimento cirúrgico. A maioria das lesões macroscópicas foram projeções papilomatosas ou em forma de verrugas. Os achados histopatológicos de todas as amostras revelaram hiperplasia da epiderme com hiperceratose, inúmeras mitoses no estrato basal, com invasões alongadas em forma de rede na derme superficial e intermediária. A MET evidenciou organismos com formas longas, afiladas e espiraladas, presumivelmente espiroquetas. Tanto as características morfológicas, quanto a resposta à terapia das lesões foram comparáveis às descritas para DD.

Heterogeneidade dos componentes de variância na produção de leite e seus efeitos nas estimativas de herdabilidade e repetibilidade

It was evaluated the heterogeneity of components of phenotypic variance and its effects on the heritability and repeatability estimates for milk yield in Holstein cattle. The herds were grouped according to their level of production (low, medium and high) and evaluated in the non-transformed, square-root and logarithmic scale. Variance components were estimated using a restricted maximum likelihood method based on an animal model that included fixed effects of herd-year-season, and as covariates the linear effect of lactation duration and the linear and quadratic effects of cow's age at calving and the random direct additive genetic, permanent environment and residual effects. In the non-transformed scale all the variance components were heterogeneous. on this scale, residual and phenotypic variance components were associated positively with the level of production while in logarithmic scale that association was negative. Estimates of heritability were more affected than the repeatability for the phenotypic variance heterogeneity and their components. The of selection process efficiency for milk production could be affected by the level of production which was considered for genetic parameters estimation.

Polimorfismos genéticos da kappa-caseína e da beta-lactoglobulina e produção de leite em bovinos

As variantes gênicas da beta-lactoglobulina (β-LG) e da kappa-caseína (κ-CN) bovinas são associadas à produção, qualidade e características de processamento do leite. O objetivo deste trabalho foi analisar as frequências dos genótipos AA, AB e BB, por meio da técnica de PCR-RFLP, da β-LG e da κ-CN bovinas, e suas associações com a produção de leite (kg leite/dia) em bovinos das raças Girolanda, Holandesa e Jersey. Para a κ-CN, a frequência do genótipo AA foi maior nos animais das raças Holandesa (37%) e Girolanda (63%). Na raça Jersey, houve predomínio do genótipo BB (60%). Para a β-LG, o genótipo AB foi o mais encontrado nas raças Girolanda (54%) e Holandesa (58%), enquanto nos animais da raça Jersey houve predomínio do genótipo BB (45%). Houve associação do alelo B da κ-CN com maior produtividade leiteira nas raças Girolanda e Holandesa, e do alelo A da β-LG com maior produtividade de leite na raça Jersey. As variantes genéticas da κ-CN podem ser usadas como marcadores na seleção para a produtividade leiteira nas raças Girolanda e Holandesa. Para a raça Jersey, as variantes da β-LG seriam mais adequadas para essa seleção.

Período seco anterior e período de serviço sobre a produção de leite e gordura na raça Holandesa no estado de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)